1. Field of the Invention
The present invention relates to novel compositions/precipitating agents comprising a polysaccharide produced by microbial fermentation and a natural polysaccharide or derivative thereof, as well as to insulating shaped articles fabricated therefrom.
2. Description of the Prior Art
Polysaccharides whose basic structural unit contains glucose and rhamnose moieties are well known to this art. They are typically prepared by fermentation of a carbon source by means of a microorganism.
Such polysaccharides and processes for the preparation thereof have been described, in particular, in published European Patent Applications No. 77,680 and No. 339,445, and in published French Patent Application No. 88/09,999.
These polysaccharides may be employed for thickening aqueous solutions and for stabilizing, or maintaining in suspension, aqueous dispersions of particles.
Furthermore, polysaccharides of natural origin are also known to this art, as are derivatives of these polysaccharides, prepared, for example, by the semi-synthetic route, and which may also be used for thickening, stabilizing or maintaining suspensions.
These natural polysaccharides are generally obtained from plants such as algae, from roots, seeds or tubers.
It has now surprisingly been found that compositions comprising such polysaccharides behave differently or even, in certain instances, in opposite manner, than as would be expected.